Colleagues,
First, yes we do remember 9/11 and we must always remember that day in infamy. I had retired earlier that year but my wife was still employed at a local law office and she called me and told me about it just after the first plane hit the Trade center and as I watched, the 2nd did. Terrible sight.
One issue that I have not seen addressed on here is clearance values or limits, especially when something crosses over a rail line, so I will inject what I remember from working with clearance diagrams and such at CSX. This was one of many things that I worked out to maintain on the CADD system I was responsible for.
The main issue facing us today is Double Stacks. In days of old and if we are setting up a simulation that does not, or did not, involve double stacks then we need about 20 feet clearance from the low rail to the bottom of whatever it is over the track. If another railroad crosses on a bridge, then the rule of thumb is that the height of a deck girder must be roughly 1/10 of the length which is why many situations involving rail over rail will use through girder spans and those insert clearance issues of their own laterally. The minimum clearance for double stacks was 27 feet but most of the time, more than that was specified, typically 30 feet. North American rail cars are typically 11 feet wide and you would want at least 1.5 feet clearance on either side. Less if it is alongside a loading dock for example, more if it is a curve on a through girder or truss bridge.
On vertical clearances you can measure the vertical clearance, just remember that it is not track to track or track to road. You must include the height of any structural members that are under the upper track or road.
On rural roads in my experience, often the roadway under the track is single lane, and the passage appears more like a tunnel than a bridge. Sometimes it is a tunnel and on the L&N there often was a L&N emblem on the side of the girder if one was involved. Those who have downloaded my "Hook & Eye" route, improved by Rick-Monon, there are some of these on the mainline just north of Etowah. There are a few on the Kingsport sub. route as well.
Jerry
First, yes we do remember 9/11 and we must always remember that day in infamy. I had retired earlier that year but my wife was still employed at a local law office and she called me and told me about it just after the first plane hit the Trade center and as I watched, the 2nd did. Terrible sight.
One issue that I have not seen addressed on here is clearance values or limits, especially when something crosses over a rail line, so I will inject what I remember from working with clearance diagrams and such at CSX. This was one of many things that I worked out to maintain on the CADD system I was responsible for.
The main issue facing us today is Double Stacks. In days of old and if we are setting up a simulation that does not, or did not, involve double stacks then we need about 20 feet clearance from the low rail to the bottom of whatever it is over the track. If another railroad crosses on a bridge, then the rule of thumb is that the height of a deck girder must be roughly 1/10 of the length which is why many situations involving rail over rail will use through girder spans and those insert clearance issues of their own laterally. The minimum clearance for double stacks was 27 feet but most of the time, more than that was specified, typically 30 feet. North American rail cars are typically 11 feet wide and you would want at least 1.5 feet clearance on either side. Less if it is alongside a loading dock for example, more if it is a curve on a through girder or truss bridge.
On vertical clearances you can measure the vertical clearance, just remember that it is not track to track or track to road. You must include the height of any structural members that are under the upper track or road.
On rural roads in my experience, often the roadway under the track is single lane, and the passage appears more like a tunnel than a bridge. Sometimes it is a tunnel and on the L&N there often was a L&N emblem on the side of the girder if one was involved. Those who have downloaded my "Hook & Eye" route, improved by Rick-Monon, there are some of these on the mainline just north of Etowah. There are a few on the Kingsport sub. route as well.
Jerry